As it is known by everybody, after the combustion of fuel, the internal combustion engines produce a certain quantity of gases in the combustion chambers, which gases must be exhausted as a condition required for the continued operation, with the new beginning of the (thermodynamic and mechanical) cycle.
The elimination of these gases has always constituted a major problem for engineering, because, not only they are a harm to health and a cause of less comfort, but also the combustion products influence directly the motor output and reduce the useful life of the equipment or the vehicle. Some of their harming characteristics are given below:
poisonous;
corrosive;
conductive of heat generated in the combustion chambers;
conductive of noise produced by the motor;
inhibitive of combustion in the next cycle;
pollution of the atmosphere.
The solutions proposed are in a great number since the invention of the explosion motor more than a century ago, in order to reduce the undesirable effects of the combustion gases. Basically, the exhaust assembly consists of one or more collectors, discharge pipes and mufflers. The exhaust collector is attached to the combustion chambers and connects, through pipings, the cylinder exhaust windows joining them in a single flanged pipe. The discharge pipe serves to collect the gases at the collector outlet and conduct them to the muffler. Normally, this pipe has many curves to bypass hindrances such as depressions in floors, shafts, and the like.
For receiving the gases from the discharge pipe and expelling them to the atmosphere, the muffler is, usually, a cylindrical box, of a circular, elliptical or oval section, the function of which is to reduce sound vibrations produced by the motor.